Process and apparatus for the production of artificial fibers and the like



y 1942- D. F. BABCOCK 2,

FROCESS AND APPARATUS F OR THE PRODUCTION-QF ARTIFICIAL AFIBERS AND THE LIKE Filed Aug. 9, 1938 in obtaining satisfactory wound packages.

Patented July 14, 1942 PROCESS AND APPARATUS FOR THE PRO- DUCTION OF ARTIFICIAL FIBERS AND THE LIKE Dale Friend Babcock, Wilmington, DeL, assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware Application August 9, 1938, Serial No. 223,983

9 Claims.

This invention relates to the production of artificial filaments, yarns, ribbons, and the like. More particularly, it relates to an improved process for the production of such artificial structures from melts of organic filamentforming compositions, for example, melts of synthetic linear polymers, which structures are subject to elongation upon exposure to atmospheric conditions. i a

In the melt spinning of synthetic linear polymer yarns, great difliculty has been experienced The difficulty was largely due to elongation of the yarn by absorption of moisture upon exposure of the wound packages of yarn to atmospheric conditions.

In the spinning of artificial filaments, yarns, ribbons, and the like from melts of organic filament-forming compositions, the filaments issue from the spinneret substantially free from absorbed moisture. Many of such organic filament-forming compositions, for example, synthetic linear polyamides, after being spun, absorb moisture from the air and as a result increase in length. Even if the dry yarn is wound on a support, such as a bobbin, under considerable tension, the increase in the length ency to elongate due to a moisture absorption from the atmosphere.

It is a further object of the present invention to provide an improved process for the spinning of molten organic filament-forming compositions, and to wind the same into a package which will not be subject to loosening of the spun product due to elongation as a result of the absorption of moisture from the atmosphere.

It is another object of this invention to provide an improved process for the spinning and winding of fibers, yarns, ribbons, and the like from molten organic filament-formirg compositions which comprises the treatment of the structure with steam between the spinneret and the wind-up position.

It is still another object of this invention to provide an improved apparatus for the steam treatment of freshly formed fibers, yarns, ribbons, and the like.

Other objects of the invention will appear hereinafter.

of the yarn accompanying moisture absorption causes the yarn to loosen on the bobbin, and the yarn tends to slip from the bobbin. The wound yarn package is consequently distorted and assumes a bumpy, blistered appearance. This results in inequalities in the yarn since the yarn in various portions of the bobbin may be free to elongate to different extents. The package formation is unsatisfactory both from the point of view of spinning operation and delivery of the thread to subsequent processes. At sufliciently low spinning speed, the filaments may pick up moisture either from the air or from liquid water applied to them in the form of a finish, or otherwise, and the greater part of the increase in length of the thread accompanying moisture absorption is brought about before the yarn is wound up under tension. At higher spinning speed, moisture applied by these means is not absorbed quickly enough, i. e., before it is wound on the bobbin, and poor package formation is the result.

It is, therefore, an object of the present invention to provide animproved method for the spinning and winding of yarns, fibers, ribbons, and the like from molten organic filament-form- The objects of the invention may be accomplished, in general, by applying to freshly formed artificial fibers, yarns, ribbons, and the like formed from molten organic filament-forming compositions, between the point where they are.

gation of the yarn in the wound package upon subsequent exposure to the atmosphere.

The nature of the invention will be more clearly apparent by reference to the following detailed description when taken in connection I with the accompanying illustration, in which:

erence numeral Figure 1 is a diagrammatic side elevational view of one form of apparatus constructed in accordance with the present invention.

Figure 2 is a side elevational view, with parts in section, showing a modified form of apparatus for the steam treatment of yarn.

Referring to Figure-l of the drawing, refll designates a spinneret through which the molten organic filamentforming composition is extruded. The extruded composition passes from the spinneret H in the form of a bundle of filaments l3, which filaments pass through a cooling chimney l5; a

cooling medium is passed through the cooling chimney IS in a direction at right angles to the passage of the bundle of filaments l3. The

ing compositions, which structures have a tend cooling medium is passed into header l1 and from the header through a plurality of conduits l9 into the cooling chimney. The cooling medium, for example, air, is passed at right angles across the bundle of filaments l3 and outwardly from the cooling chimney l5 through a plurality of perforations 2|. The bundle of filaments is passed from the cooling chimney through a steam treatment enclosure 23. A quantity of steam is passed into the enclosure 23 through header 25 and branch conduits 21. The volume of steam may be controlled by means of valve 29. Any condensed steam which may form within the steam treatment enclosure 23 will pass to the bucket 3| at the bottom of the enclosure from which the water may be withdrawn through conduit 33.

After passage of the bundle of filaments through the steam treatment enclosure 23, they are passed into contact with a liquid finish applicating roller 35. The bundle of filaments is then passed around feed rolls 3'! and 39 and is then wound onto bobbin 40.

In the modified form of steam treatment enclosure shown in Figure 2 of the drawing, reference numeral 50 designates a cylindrical enclosure in which steam is applied to the bundle of filaments IS. The enclosure 50 is provided with a sleeve 52 which is smaller in diameter than the diameter of the enclosure 50. A steam jacket 54 is positioned around the enclosure 50. A steam inlet 56 is connected at the upper portion of the steam jacket and an outlet for the steam is provided at 59 at the bottom of said steam jacket. The steam, in this modification, is preferably under pressure considerably above atmospheric. Steam is passed from the jacket 54 to the enclosure 50 through the small ope gs 58. The steam under pressure passes against sleeve 52, and then fills the enclosure. The steam is not permitted to condense on the walls of the enclosure 50, since the temperature of such walls is above the condensation point of the steam. This is obviously due to the fact that the steam in the jacket surrounding the enclosure has a pressure above atmospheric. The only condensation of steam within the enclosure 50 is, therefore, on the bundle of filaments l3. This modified form of steaming enclosure is preferably provided with threading means for threading the thread through the enclosure. The threading means comprises a short conduit 60 which passes through the walls of the steam jacket and the enclosure 50. The outwardly projecting end of conduit 60 is connected to a source of a fluid underpressure. The conduit 60 is positioned to slant obliquely downwardly so as to move a bundle of filaments by means of a fluid such as air downwardly through the steam treatment chamber 50. After the threading operation the air is turned off.

The following specific examples are submitted to illustrate the specific details of the invention as applied to filaments, yarns, ribbons, and the like spun from molten synthetic linear polymers. It is to be understood that the invention is not limited to the specific details set forth in these illustrative examples.

Example I Solid particles of polyhexamethylene adipamide, having a melt viscosity of approximately 300 poises, were fed into a nitrogen-filled melt chamber onto a melting element maintained at 285 C. The polymer melted and formed a pool beneath the melting element from which it was pumped, by means of a gear pump, into a screen pack having a diameter of about and comprising approximately ten 16-mesh (l. e., 16 meshes per inch), three 30-mesh, three BO-mesh, ten -mesh, one hundred twenty-five ZOO-mesh, and ten 325-mesh screens. The polymer was forced through a spinneret having an outside diameter of about 1" and containing 15 perforations of approximately 0.006" in diameter located on a diameter circle. The yarn after issuing from the spinneret entered the cooling chimney where it was cooled and solidified by air traveling at right angles to the direction of the thread at about a rate of 18 cu. ft. a minute. The yarn after passing from the cooling chimney was passed through theatmosphere for a distance of about 10", and then passed into the steam treatment enclosure which was approximately 45" in length. Steam was supplied to the steam treatment enclosure in such an amount that it gently but Just visibly issued from the top and bottom of the enclosure. A suitable finish was applied to the yarn from a water emulsion by means of a roll positioned about 4" below the bottom of the steam treatment enclosure. After traveling a distance of about 12" downwardly from the finish applicating roller, the yarn passed about two feed rolls positioned about 19" apart and was then led to a bobbin positioned about 36" from the second feed roll and there wound into the form of a yarn package. The yarn was wound at the rate of 3500 feet per minute and the pump rate so adjusted that the denier of the yarn was approximately 153. The peripheral speed of the second feed roll was 0.75% less than that of the wind-up bobbin in order to apply tension to the yarn. For the same reason the peripheral speed of the first feed roll was 0.50% less than that of the second feed roll. Under these conditions a bobbin containing about one pound of yarn was wound and gave excellent compact package formation. When this bobbin of yarn was stored for two days over water no blisters appeared and the package of yarn remained tight on the bobbin.

If, in the above example, no steam is passed through the steam treatment enclosure, but with all other conditions remaining the same, only a small quantity of yarn can be wound onto a bobbin. Even if water is appliedto the surface of the yarn at a point just below the steam treatment enclosure, only a small package can be wound. Bad irregularities and blisters appear on the surface of the package after it is stored for about one hour in an atmosphere having a relative'humidity of about 60%.

Example II Yarn of 150 denier and 11 filaments is spun at a speed of 2670 feet per minute from molten polyhexamethylene adipamide in a manner similar to that described in the preceding example. The peripheral speed of the second feed roll is 0.25% less than the peripheral speed of the bobbin, and the peripheral speed of the first feed roll is 0.25% less than the peripheral speed of the second roll. The steam treatment enclosure, the top of which is placed about 10" below the bottom of the cooling chamber, is constructed as illustrated in Figure 2 of the drawing. Steam is passed through the jacket surrounding the steam treatment enclosure at 10 to 12 pounds pressure. Steam is passed from the jacket to the enclosure through a small opening, such as opening 58 shown in Figure 2, which opening has a diameter of about of an inch. The steam is de flected downwardly by means of sleeve I2 so as not to disturb the thread. Under these conditions, bobbins of yarn are produced which contain over one pound of yarn, and in which the yarn does not loosen or blister even when the packages are exposed to atmosphere having a high relative humidity.

As pointed out above the length of the steam treatment enclosure required will depend on the thread speed and the yarn and filament deniers. For example, when spinning 150 denier yarn with 11 filaments at a speed of 3300 feet per minute, the use of a steam treatment enclosure having a length of 45" results in the production of a yarn package which will become only slightly soft after two days storage over water. "The use of a steam treatment enclosure having a length of 25" under the same conditions will result in the production of a yarn package which is somewhat softer than that obtained with a longer enclosure; however, packages produced from an enclosure of this length under the above-mentioned conditions will be satisfactory. n the other hand, if the steam treatment enclosure is reduced to a length of 11" under the above-mentioned conditions, the threading of the yarn is not sufiicient to produce a completely satisfactory package of yarn. As a general rule for the spinning of yarns and filaments of the usual deniers used in textile fabrics, a steam treatment enclosure having such a length that it will subject the yarn to treatment with steam for a pei harmed and the package formation is good. At

lower thread speeds, for example, thread speeds of the order of 1,000 feet per minute, fair package formation can be obtained by the application of water to the yarn at a point just below the cooling chamber. However, even under these conditions, just the right amount of water must be applied. If too much water is applied, surface water remains on the yarn when it is wound up on the bobbin and the yarn slips and slides so that the package spreads out during spinning. If there is too small a quantity of water applied to the yarn, the package blisters in the manner above described. Therefore, even in the case of low thread speeds, the present invention has a distinct advantage.

Although the present invention is described with particular reference to synthetic linear polyamides, it is obviously broadly applicable to the melt spinning of any organic filament-forming materialin which the spun product will elongate upon subsequent contact with the atmosfihere containing the usual moisture content.

Therefore, besides being applicable to the spinwherever the difliculty of elongation upon subsequent exposure to the atmosphere occurs.

Likewise, filaments, yams or ribbons may contain modifying agents such as delusterants, plasticizers, pigments, dyes, antioxidants, resins, etc, without interfering with the operativeness of the present invention.

The present invention has been described with specific reference to the use of steam for the treatment of the filaments, yarns, and the like.

Although steam is much preferred, the objects can be substantially accomplished by the use of air, or other gaseous medium having an elevated temperature and a high relative humidity. It is preferred, in accordance with this modification of the invention, to use air or the like having a temperature above 150 F. and having a relative humidity of at least 90%.

Many modifications of the design of suitable steam treatment enclosures may be used. It is only essential that the yarn be kept in contact with steam for a suflicient time to pick up the required amount of moisture. For ease in threading, the steaming enclosure might be provided with a narrow slot along the length of the steaming enclosure through which the yarn may he slipped, and this slot may be furthermore provided with spring pressed covering means so that the slot may be covered after the yarn is positioned in the enclosure.

Although feed rolls for drawing the thread through the above-described apparatus are preferred, they are not essential to the invention. If no feed roll is used in the apparatus, the yarn will be passed from the spinneret through the treatment membersand wound directly on a rotating bobbin. Guides of any desired design may be used for furnishing the necessary tension inplace of feed rolls. If the steam is applied to the yarn between the feed rolls, or between the last feed roll and the bobbin, the speed of the second feed roll and the bobbin in the first case, or the bobbin in the second case, would have to be greater than that of the first, or the first and second feed rolls to allow for the elongation of the yarn as it absorbs moisture.

-The use of steam between the spinneret and the wind-up, in accordance with the present invention, makes it possible for the yarn to absorb 'moisture and increase in length before it is wound up under tension on the bobbin. Steam conditioned yarn appears to undergo much less change in dimensions with changes in humidity of the surrounding atmosphere than does unconditioned yarn. This apparently is not due to a smaller change in moisture content because of higher initial content, but seems -to' be an inherent property of the steamed yarn. For example, when samples of steamed and unsteamed ning of filaments and the like from synthetic acetals, and various interpolymers such as polyester-polyamides, etc. It is also applicable to the melt spinning of ethylene polymers, vinyl polymers, polystyrene and polyacrylic acid derivatives as well as some cellulose derivatives,

yarn are held over CaCla overnight, then measured, and subsequently wet with water and. again measured, the unsteamed sample will elongate approximately 6% and the steamed sample approximately 3%. This indicates that the effect of steaming is not merely humidification.

This is very surprising and is a very valuable property since it facilitates handling of the yarn especially when transferring it from package to package during textile operations.

Steam treatment of yarn between the spinneret and the wind-up roll makes it possible to spin fibers from melts at a high rate, 1. e., above 1,000 feet per minute, and obtain well-built packages on bobbins which will not blister or loosen on the wound package. As above indicated, the use of water is particularly ineffective for the purposes and objects of the present invention when spinning at high rates oi. speed. Yarn steam treated in accordance with the present invention undergoes less change in dimension with changes in humidity 01 the surrounding atmosphere than similar untreated yarns, and they are less susceptible to changes in relative humidity of the atmosphere. Humidity control and air conditioning in the spinning room are not required when yarns are steam treated in accordance with the present invention.

Obviously, many other changes and modifications can be made in the above-described method and apparatus without departing from the nature and spirit of the present invention. It is, therefore, to be understood that the invention is not to be limited except as set forth in the appended claims.

I claim:

1. In a process which includes the spinning of a molten composition of a synthetic linear polymer in the form of a continuous structure, the passsing of the structure through a solidification zone, and the winding of the solidified structure, without cold drawing the same, in the form of a package, the step which comprises contacting said structure, between said solidification zone and the point where said structure is wound, with a gaseous medium having a temperature of at least 150 F. and a relative humidity of at least 90%, whereby the tendency of said structures to elongate in said package is reduced.

2. In a process which includes the spinning of a molten composition of a synthetic linear polymer in the form of a continuous structure, the passing of the structure through a solidification zone, and the winding of the solidified structure, without cold drawing the same, in the form of a package, the step which comprises contacting said structure, between said solidification zone and the point where said structure is wound, with steam, whereby the tendency of said structures to elongate in said package is reduced.

3. In a process which includes the spinning of a molten composition of a synthetic linear polymer in the form of a continuous structure, the passing of the structure through a solidification zone, and the winding of the solidified structure, without cold drawing the same, in the form of a package, the step which comprises contacting said structure, between said solidification zone and the point where said structure is wound, with steam at atmospheric pressure, whereby the tendency of said structures to elongate in said package is reduced.

4. In a process which includes the spinning of a molten composition of a synthetic linear polymer in the form of a continuous structure, the passing of the structure through a solidification zone, and the winding of the solidified structure, without cold drawing the same, in the form of a package, the step which comprises contacting said structure, between said solidification zone and the point where said structure is wound, with steam above atmospheric pressure, whereby the tendency of said structures to elongate in said package is reduced.

5. In a process which includes the spinning of a molten composition of a synthetic linear polymer. in the form 01 a continuous structure, the passing of the structure through a solidification zone, and the winding of the solidified structure, without cold drawing the same, in the form of a package, the step which comprises contacting said structure, between said solidification zone and the point where said structure is wound,

with steam for a period of at least 0.04 second,

whereby the tendency of said structures to elongate in said package is reduced.

6. In a process which includes the spinning of a molten composition oi. a synthetic linear polymer in the form of a continuous structure, the passing of the structure through a solidification zone, and the winding of the solidified structure, without cold drawing the same, in the form of a package, the step which comprises contacting said structure, between said solidification zone and the point where said structure is wound, with steam, and subjecting the steamed structure to tension, whereby the tendency of said structures to elongate in said package is reduced.

7. In a process which includes the spinning of a molten composition of a synthetic linear polyamide in the form of a continuous structure, the passing of the structure through a solidification zone, and the winding of the solidified structure, without cold drawing the same, in the form of a package, the step which comprises contacting said structure, between said solidification zone and the point where said structure is wound, with a gaseous medium having a temperature of at least 150 F. and a'relative humidity of at least whereby the tendency of said structures to elongate in said package is reduced.

8. In a process which includes the spinning of a molten composition of a synthetic linear polyamide in the form of a continuous structure, the passing of the structure through a solidification zone, and the winding of the solidified structure, without colddrawing the same, in the form of a package, the step which comprises contacting said structure, between said solidification zone and the point where said structure is wound, with steam, whereby the tendency of said structures to elongate in said package is reduced.

9. In an apparatus for the steam treatment of structures formed by the melt spinning of organic filament-forming compositions, a steam treatment enclosure, a steam jacket surrounding the said enclosure, inlet and outlet means for passing steam through said jacket, and an opening between said jacket and said enclosure for passing a small quantity of said steam from said jacket to said enclosure.

DALE FRIEND BABCOCK. 

